Hexanuclear Copper(I) Hydride from the Reduction-Induced Decarboxylation of a Dicopper(II) Formate

Jana Lücken; Thomas Auth; Sara Ida Mozzi; Franc Meyer

doi:10.1021/acs.inorgchem.0c02126

Hexanuclear Copper(I) Hydride from the Reduction-Induced Decarboxylation of a Dicopper(II) Formate

Inorg Chem. 2020 Oct 5;59(19):14347-14354. doi: 10.1021/acs.inorgchem.0c02126. Epub 2020 Sep 17.

Authors

Jana Lücken¹, Thomas Auth², Sara Ida Mozzi¹, Franc Meyer^{1

3}

Affiliations

¹ Institute of Inorganic Chemistry, University of Göttingen, Tammannstraße 4, D-37077 Göttingen, Germany.
² Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstraße 2, D-37077 Göttingen, Germany.
³ International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, D-37077 Göttingen, Germany.

PMID: 32941732
DOI: 10.1021/acs.inorgchem.0c02126

Abstract

Copper(I) hydride complexes represent a promising entry into formic acid dehydrogenation catalysis. Herein we present the spontaneous decarboxylation of a μ_1,3-formate-bridged dicopper(II) complex (1^H) to a hexacopper(I) hydride cluster (2^H) upon reduction. Isotopic labeling studies revealed that both the H^- and CO₂ originate from the bound μ_1,3-formate in 1^H, which represents a key step of the metal-mediated formic acid dehydrogenation. The full reaction equation for the conversion of 1^H to 2^H is established. The structure of 2^H features two Cu₃ triangles, each capped by a hydride ligand. Typical hydride reactivity of 2^H is demonstrated by the addition of phenylacetylene, leading to the replacement of the hydrides by alkynide ligands ^-C≡CPh (3) while retaining the hexacopper(I) core. Temperature-dependent dynamic behavior in solution on the NMR time scale was observed for both 2^H and 3, reflecting the rich structural landscape of the bis(pyrazolate)-bridged hexacopper(I) core (four isomers each for 2^H and 3) predicted by DFT calculations.